Sepsis is a significant healthcare issue due to its high frequency of occurrence and high mortality rate in hospitals. One of the leading causes of sepsis is a bloodstream infection (BSI). BSI is most commonly diagnosed by a blood culture, in which a sample of blood is incubated with a microorganism growth media in an atmosphere controlled to promote bacterial growth. Current automated blood culture systems can take 12-48 hours to detect the presence of infectious microorganisms in blood and can take up to 5 days to rule out the presence of any infectious microorganisms. Often times, additives must be combined with the blood culture to ensure that the presence or absence of a BSI is determined as quickly and accurately as possible. For example, a patient's blood at the time of sampling already contains antibiotics. The presence of antibiotics can further increase the time required to detect the presence of infectious microorganisms. Furthermore, it can take up to an additional 12-48 hours to identify the infection microorganisms by sub-culturing the positive blood culture and performing identification and antimicrobial susceptibility tests. These results can be too late to alter the treatment course and result in the death of the patient.
Adsorption resins of various kinds can be used to adsorb the presence of antibiotics in a patient's blood sample in order to reduce the time required to detect the presence of infectious microorganisms. In addition, adsorption of antibiotics from the patient's blood sample allows the microorganisms to recover and grow, thereby confirming the presence of those microorganisms in the sample. The adsorption resin and microorganism growth media are typically present in one mixture disposed in a sealed container. In addition to reducing the time of microorganism detection by mitigating the effects of antibiotics on microorganism growth, blood samples are often filtered to capture any microorganisms if present, for a faster bacterial time to detection. However, the practice is currently performed in a general microbiology laboratory with multiple tools and steps.
It has been discovered that certain components of an optimized media formulation are incompatible with resins. For example, when a lytic media is present in the mixture containing adsorption resin and a growth media, the adsorption resin may adsorb components of the lytic reagent. Such adsorption results in a loss of lytic function. Separating the lysis reagent from the resin and culture media in a single closed system is desired in order to enhance the stability of the media and to minimize non-specific adsorption of the media components that are necessary for microorganism growth (e.g., nutrients, detergents, etc.). Therefore, improved methods and apparatuses for combining additives to blood cultures, and processing blood samples for diagnosis of BSI continue to be sought.